Electrocapillary Curves for the Hg/Ionic Liquid Interface
Andrzej Lewandowski, Tomasz Majkowski, and Maciej Galinski
Faculty of Chemical Technology, Pozna´n University of Technology, PL-60 965 Pozna´n, Poland Reprint requests to A. L.; Fax: +48 61 662 571; E-mail: andrzej.lewandowski@put.poznan.pl Z. Naturforsch.64a,263 – 268 (2009); received April 15, 2008 / reveised September 2, 2008
Electrocapillary curves (surface tensionγas a function of the electrode potentialE) for a series of room-temperature ionic liquids (RTILs) were measured using a mercury dropping electrode with the drop-weight (drop-volume) technique. The curvesγ= f(E) for the Hg/RTIL interface have one maximum and may be approximated with a polynomial of sixth-order. There are no ‘humps’ in the curves. The interfacial tension of the Hg/RTIL system changes with potentialEin a monotonic way.
The second derivative ofγ=f(E) leads to a polynomial of fourth order, indicating the capacitance of the Hg/RTIL interface. The potential of zero charge is within a relatively narrow range. The specific capacitance at the minimum is of the order 10µF/cm2.
Key words:Ionic Liquid; Electrocapillary Curve.